In 1923, when the first botanists surveyed the atoll, Kure's vegetation was still predominantly native. However, the construction of a radar reflector in 1955, and the installation of a Coast Guard LORAN station, a 625-foot radio tower, and a 4000-foot runway that was maintained around the clock from 1960 to 1993, greatly altered the flora on Kure. Today, we find few of the original endemics that were common up until 1960. Additionally, there are a host of nonnatives that have thoroughly invaded the island and, in areas, completely converted the flora to a mix of pantropical weeds. Nonetheless, Kure still supports large stands of many native plants, some of which are found in very few other places.

Source: http://www.hear.org/starr/publications/botanical_inventory_of_kure_text.pdf

Among the most prominent plants on Kure is the weed Verbesina encelioides, a member of the sunflower family. The plant grows to 5 feet tall, and has almost entirely taken over more than half the area of Kure and other atolls, including Midway. V. encelioides presents a significant problem of habitat degradation for seabirds and native plants from decrease of potential nesting habitat and inhibition of native plant growth.

Source: http://www.hear.org/starr/hiplants/images/thumbnails/html/verbesina encelioides.htm